• Korean Journal of Pharmacognosy
• /
• v.32 no.4 s.127
• /
• pp.287-291
• /
• 2001

The Radix of Gentiana macrophylla (Gentianaceae) has been used for dispelling wind-damp, relaxing the sinews, and clearing heat from deficiency. In order to evaluate its quality, the method for the quantitative determination of gentiopicroside as standard compound has been developed. Gentiopicroside was a major compound of Gentianae Macrophyllae Radix. It was analyzed by HPLC using 30% MeOH as a solvent system. The amount of gentiopicroside from Gentianae Macrophyllae Radix was in the range of $2.22{\pm}1.22%\;(n=18)$.

• Animal Systematics, Evolution and Diversity
• /
• v.33 no.4
• /
• pp.262-266
• /
• 2017

Flies of the genus Scatella are small and dark-gray, and many species have distinctive whitish spots on their gray wings. Most species are found in damp environment, such as the borders of marshes, seashore areas, swamps, lakes, ponds, streams, and paddy fields. The Korean shore fly genus Scatella Robineau-Desvoidy has been taxonomically noted. A total of five species have been identified: S. calida Matsumura, 1915, S. nipponica Miyagi, 1977, S. obsoleta Loew, 1861, S. paludum (Meigen, 1830), and S. tenuicosta Collin, 1930. This is the first report of S. calida Matsumura, 1915 from Korea. A key to the Korean Scatella species and photographs of the external features have been provided.

• Current Photovoltaic Research
• /
• v.8 no.1
• /
• pp.12-16
• /
• 2020

This study investigates the degradation characteristics of different material types of ethyl vinyl acetate (EVA) and polyolefin (POE) with combining transparent backsheet. To this end, we fabricated samples with structure of glass/encapsulant/transparent backsheet for each type of encapsulants, and shingled Si modules with the same structure. The samples were then subjected to accelerated test by storing under damp heat condition of 85℃ and 85% RH. As a result, encaplsulant discoloration was observed, which the transmittance of the samples with EVA decreased in a rapid rate than the samples with POE. The discoloration also affected a power degradation of the shingled modules with a reduction of current density, resulting that the module with EVA showed more drop on the efficiency than the modules with POE. Furthermore, corrosion of the soldered ribbon caused by acetic acid produced from the degraded EVA also contributed in fill factor reduction.

• Bulletin of the Korean Mathematical Society
• /
• v.53 no.3
• /
• pp.843-852
• /
• 2016

A vortex sheet is susceptible to the Kelvin-Helmhotz instability, which leads to a singularity at finite time. The vortex blob model provided a regularization for the motion of vortex sheets in an inviscid fluid. In this paper, we consider the blob model for viscous vortex sheets and present a linear stability analysis for regularized sheets. We show that the diffusing viscous vortex sheet is unstable to small perturbations, regardless of the regularization, but the viscous sheet in the sharp limit becomes stable, when the regularization is applied. Both the regularization parameter and viscosity damp the growth rate of the sharp viscous vortex sheet for large wavenumbers, but the regularization parameter gives more significant effects than viscosity.

• Journal of Advanced Navigation Technology
• /
• v.4 no.2
• /
• pp.132-142
• /
• 2000

This paper includes a study on the performance analysis of SDINS by a simulator using Matlab/Simulink. The performance model is considered gravity and Coriolis force, and a barometer is included to damp down diversity of a perpendicular axis error. Using the simulator, the performance included gyro sensor errors was analyzed in various maneuvering patterns. Also, the performance is virtually presented for the variation of error parameters of gyro and accelerometer under GUI.

• Proceedings of the KIPE Conference
• /
• 2004.07a
• /
• pp.415-419
• /
• 2004

The U filter has been generally used to filter the output voltage of PWM inverter to the sinusoidal waveform. The resonant voltage on the output voltage of PWM inverter may be generated due to LC filter. This paper proposed the algorithm to damp the resonant voltage using the virtual resistor without decreasing the efficiency by the power loss in the real resistor The method is appled to the vector controlled induction motor driven by the PWM inverter with the LC filter. The simulation results are carried out to verify the performances of the proposed algorithm.

• Proceedings of the KIEE Conference
• /
• 2000.07a
• /
• pp.516-518
• /
• 2000

This paper presents a methodology for effective control of fuel cell devices connected to the electric utility distribution network. A controller is designed for a fuel cell power plant to assist the conventional generators to damp out oscillations, which is possible by utilizing the fast response characteristic of fuel cells. Computer model of the controller is proposed and its effectiveness is proved by a sample test. Fuel cell devices can be used to improve power system stability when these are connected to a distribution system.

• Proceedings of the KIEE Conference
• /
• 1998.11c
• /
• pp.1033-1036
• /
• 1998

In this research project, two aspects of small signal stability are studied: improvement in Hessenberg method to compute the dominant electromechanical oscillation modes and siting FACTS devices to damp the low frequency oscillation. Fourier transform of transient stability simulation results identifies the frequencies of the dominant oscillation modes accurately. Inverse transformation of the state matrix with complex shift equal to the angular speed determined by Fourier transform enhances the ability of Hessenberg method to compute the dominant modes with good selectivity and small size of Hessenberg matrix. Any specified convergence tolerance is achieved using the iterative scheme of Hessenberg method. Siting FACTS devices such as SVC, STACOM, TCSC, TCPR and UPFC has been studied using the eigen-sensitivity theory of augmented matrix. Application results of the improved Hessenberg method and eigen-sensitivity to New England 10-machine 39-bus and KEPCO systems are presented.

• International Journal of Control, Automation, and Systems
• /
• v.3 no.spc2
• /
• pp.262-269
• /
• 2005

In this paper, a nonlinear robust control approach is applied to design a controller for the Static Synchronous Compensator (STATCOM). A robust control dynamic model of STATCOM in a one-machine, infinite-bus system is established with consideration of the torque disturbance acting on the rotating shaft of the generator set and the disturbance to the output voltage of STATCOM. A novel recursive approach is utilized to construct the energy storage function of the system such that the solution to the disturbance attenuation control problem is acquired, which avoids the difficulty involved in solving the Hamilton-Jacobi-Issacs (HJI) inequality. Sequentially, the nonlinear disturbance attenuation control strategy of STATCOM is obtained. Simulation results demonstrate that STATCOM with the proposed controller can more effectively improve the voltage stability, damp the oscillation, and enhance the transient stability of power systems compared to the conventional PI+PSS controller.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.6
• /
• pp.704-711
• /
• 1999

This paper presents a design of fuzzy power system stabilizer (FPSS) using adaptive evolutionary computation (AEC). We have proposed an adaptive evolutionary algorithm which uses a genetic algorithm (GA) and an evolution strategy (ES) in an adaptive manner in order to take merits of two different evolutionary computations. FPSS shows better control performances than conventional power system stabilizer (CPSS) in three-phase fault with heavy load which is used when tuning FPSS. To show the robustness of the proposed FPSS, it is appliedto damp the low frequency oscillations caused by disturbances such as three-phase fault with normal and light load, the angle deviation of generator with normal and light load and the angle deviation of generator with heavy load. Proposed FPSS shows better robustness than CPSS.